/*******************************************************************************
* Copyright 2018 Intel Corporation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*******************************************************************************/

/*
 * Cell execution GRU with linear before reset
 */

#include "math_utils.hpp"
#include "mkldnn_thread.hpp"

#include "ref_rnn.hpp"

namespace mkldnn {
namespace impl {
namespace cpu {

using namespace mkldnn::impl::utils;
using namespace mkldnn::impl::math;
using namespace rnn_utils;
#define AOC array_offset_calculator

template <>
rnn_elemwise_sig(ref_rnn_fwd_f32_t::gru_lbr_elemwise) {
    ws_gates_aoc_t ws_gates(rnn, ws_gates_);
    bias_aoc_t bias(rnn, bias_);
    ws_states_aoc_t states_t_l(rnn, states_t_l_);
    ws_states_aoc_t states_tm1_l(rnn, states_tm1_l_);
    ws_gates_aoc_t ws_gemm_state(rnn, ws_cell_);
    AOC<float, 2> ws_Wh_b(ws_grid_, rnn.mb, rnn.dic);

    parallel_nd(rnn.mb, [&](int i) {
        PRAGMA_OMP_SIMD()
        for (int j = 0; j < rnn.dic; j++) {
            float Wh_b = ws_gemm_state(i, 2, j) + bias(3, j);
            ws_gates(i, 0, j) = logistic_fwd(
                    ws_gates(i, 0, j) + ws_gemm_state(i, 0, j) + bias(0, j));
            ws_gates(i, 1, j) = logistic_fwd(
                    ws_gates(i, 1, j) + ws_gemm_state(i, 1, j) + bias(1, j));
            ws_gates(i, 2, j) = tanh_fwd(
                    ws_gates(i, 2, j) + ws_gates(i, 1, j) * Wh_b + bias(2, j));
            states_t_l(i, j) = states_tm1_l(i, j) * ws_gates(i, 0, j)
                    + (1.0f - ws_gates(i, 0, j)) * ws_gates(i, 2, j);
            if (rnn.is_training)
                ws_Wh_b(i, j) = Wh_b;
        }
    });
}

template <>
rnn_elemwise_sig(ref_rnn_fwd_u8s8_t::gru_lbr_elemwise) {
    assert(!"GRU LBR int8 is not supported");
}

template <>
rnn_cell_execution_sig(ref_rnn_fwd_f32_t::cell_execution_gru_lbr) {
    if (!rnn.merge_gemm_layer) {
        (this->*gemm_layer_func)('N', 'N', rnn.n_gates * rnn.dic, rnn.mb,
                rnn.slc, 1.0, w_layer_[0], rnn.weights_layer_ld,
                states_t_lm1_, rnn.states_ws_ld, 0.0, ws_gates_,
                rnn.gates_ws_ld);
    }
    (this->*gemm_iter_func)('N', 'N', rnn.n_gates * rnn.dic, rnn.mb, rnn.sic,
            1.0, w_iter_[0], rnn.weights_iter_ld, states_tm1_l_,
            rnn.states_ws_ld, 0.0, ws_cell_, rnn.gates_ws_ld);
    (this->*elemwise_func)(rnn, ws_gates_, states_t_l_, c_states_t_l_,
            states_tm1_l_, c_states_tm1_l_, diff_states_t_l_,
            diff_states_t_lp1_, diff_states_tp1_l_, bias_[0], ws_grid_,
            ws_cell_);
}

template <>
rnn_cell_execution_sig(ref_rnn_fwd_u8s8_t::cell_execution_gru_lbr) {
    assert(!"GRU LBR int8 is not supported");
}

template <>
rnn_elemwise_sig(ref_rnn_bwd_f32_t::gru_lbr_elemwise) {
    ws_gates_aoc_t ws_gates(rnn, ws_gates_);
    ws_states_aoc_t states_tm1_l(rnn, states_tm1_l_);
    ws_diff_states_aoc_t diff_states_t_l(rnn, diff_states_t_l_);
    ws_diff_states_aoc_t diff_states_tp1_l(rnn, diff_states_tp1_l_);
    ws_diff_states_aoc_t diff_states_t_lp1(rnn, diff_states_t_lp1_);
    ws_gates_aoc_t ws_gates_r(rnn, ws_cell_);
    AOC<float, 2> ws_Wh_b(ws_grid_, rnn.mb, rnn.dic);

    // 1. calculate dG1 dG2 dG3
    // dG0 = (dht - G2) * dht * (1 - G0) * G0
    // dG1 = (W*h + b) * dG2 * (1 - G1) * G1
    // dG2 = (1 - G0) * dht * (1 - G2*G2)
    parallel_nd(rnn.mb, [&](int i) {
        PRAGMA_OMP_SIMD()
        for (int j = 0; j < rnn.dic; j++) {
            float h = states_tm1_l(i, j);
            float dHt = diff_states_tp1_l(0, i, j)
                    + diff_states_t_lp1(rnn.n_states, i, j);
            float dG0 = (h - ws_gates(i, 2, j)) * dHt
                    * x_m_square(ws_gates(i, 0, j));
            float dG2 = (1.0f - ws_gates(i, 0, j))
                    * one_m_square(ws_gates(i, 2, j)) * dHt;
            float dG1 = ws_Wh_b(i, j) * dG2 * x_m_square(ws_gates(i, 1, j));

            diff_states_t_l(0, i, j) = dHt * ws_gates(i, 0, j);
            ws_gates(i, 2, j) = dG2;
            ws_gates_r(i, 2, j) = dG2 * ws_gates(i, 1, j);
            ws_gates(i, 0, j) = ws_gates_r(i, 0, j) = dG0;
            ws_gates(i, 1, j) = ws_gates_r(i, 1, j) = dG1;
        }
    });
}

template <>
rnn_cell_execution_sig(ref_rnn_bwd_f32_t::cell_execution_gru_lbr) {
    ws_gates_aoc_t ws_gates_r(rnn, ws_cell_);
    ws_diff_states_aoc_t diff_states_t_l(rnn, diff_states_t_l_);

    (this->*elemwise_func)(rnn, ws_gates_, states_t_l_, c_states_t_l_,
            states_tm1_l_, c_states_tm1_l_, diff_states_t_l_,
            diff_states_t_lp1_, diff_states_tp1_l_, bias_[0], ws_grid_,
            ws_cell_);

    if (!rnn.merge_gemm_layer) {
        //  dx = dG * Wx^t
        (this->*gemm_layer_func)('N', 'N', rnn.slc, rnn.mb,
                rnn.n_gates * rnn.dic, 1.0, w_layer_[0],
                rnn.weights_layer_ld, ws_gates_, rnn.gates_ws_ld, 0.0,
                &diff_states_t_l(rnn.n_states, 0, 0), rnn.states_ws_ld);
        // dWx +=  dG^t * x
        gemm('N', 'T', rnn.n_gates * rnn.dic, rnn.slc, rnn.mb, 1.0, ws_gates_,
                rnn.gates_ws_ld, states_t_lm1_, rnn.states_ws_ld, 1.0,
                diff_w_layer_, rnn.diff_weights_layer_ld);
    }
    // dh +=  dGr * Wh^t
    (this->*gemm_iter_func)('N', 'N', rnn.sic, rnn.mb, rnn.n_gates * rnn.dic,
            1.0, w_iter_[0], rnn.weights_iter_ld, ws_cell_, rnn.gates_ws_ld,
            1.0, diff_states_t_l_, rnn.states_ws_ld);

    // dWh += dGr^t * h
    gemm('N', 'T', rnn.n_gates * rnn.dic, rnn.sic, rnn.mb, 1.0, ws_cell_,
            rnn.gates_ws_ld, states_tm1_l_, rnn.states_ws_ld, 1.0, diff_w_iter_,
            rnn.diff_weights_layer_ld);

    // db1-3 += e * dG
    // db4 += e * (r * dG2)
    gates_reduction(rnn, ws_gates_, diff_bias_);

    parallel_nd(rnn.dic, [&](int j) {
        for (int i = 0; i < rnn.mb; i++) {
            diff_bias_[3 * rnn.dic + j] += ws_gates_r(i, 2, j);
        }
    });
}

#undef AOC

}
}
}